A similar inhibition of the upregulation of MMP-2 and MMP-9 by PRO has also been reported in nasopharyngeal carcinoma [59], pancreatic cancer [50, 53], gastric adenocarcinoma [66], melanoma [106], prostate cancer [107] and of MMP-9 in medulloblastoma [108] and infantile hemangioma [109–110]. Here, MMP9 is linked to prostate cancer.